JBoss Seam

Exploring the Strengths of Seam

1. The first application framework for
EJB 3.0

EJB 3.0 has totally changed the notion of EJB components as coarse-grained, heavyweight objects to EJBs as lightweight POJOs with fine-grained annotations. Seam eliminates the distinction between the presentation tier components and the business logic components and brings a uniform component model to the EE platform where any class may be an EJB.

Seam is providing a backward compatibility with JEE i.e. it is not limited to Java EE 5.0 servers that support EJB 3.0. Seam may be used in any JEE environment, or even in plain Tomcat.

2. Integrate and Enhance Java EE Frameworks

The core frameworks included in Java EE 5.0 are JSF 1.2 and EJB3.0. EJB 3.0 is nothing but the light weight middle tier framework based on POJO (Plain Old Java Objects). It is used for data persistence and business services. JSF is the component framework based on MVC architecture meant for web applications development. Most of the web applications based on Java EE 5.0 do not have both EJB3 and JSF modules for business logic and front end respectively. EJB3 configures services by using annotations while JSF uses XML files. Furthermore at the framework level EJB 3.0 and JSF components are not aware of each other. Artificial facade objects enable the EJB 3 and JSF components to work together by tying
  up the business components to web pages and boilerplate code so that the method calls can be made across the framework boundaries. Seam is responsible for gluing these technologies together. Seam breaks the artificial layer between EJB3 and JSF and also integrates EJB3 and JSF by using consistent and annotation-based approach. Seam lets the developer to use the “same kind of stuff”, annotated POJOs for all the components of any application. Seam applications are quite simple and includes less significant code (for both Java as well as XML code) while having the same functionality.

3. Web 2.0 Ready

Seam is mainly designed for the web applications of the Web 2.0 style. Seam supports AJAX (Asynchronous JavaScript and XML) in various ways such that the Seam components can directly access the custom JavaScript library from the browser like a JavaScript object. Seam supports an advanced concurrency model that internally manages multiple AJAX requests of a single user.

AJAX applications simplifies the frequent requests to the server as compared to non- AJAX applications. However the frequent requests make it challenging to handle the increase in database load. The database can not handle the load if the database serves all the request. To combat this challenging job Seam provides an in-memory cache, which provides a stateful persistence context. This in-memory cache is capable to hold the information throughout the session and hence,
Oct 2007 | Java Jazz Up | 27
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